Fix: ensure kernel context is in a list before trying to delete it

[lttng-tools.git] / src / bin / lttng-sessiond / kernel.c

diff --git a/src/bin/lttng-sessiond/kernel.c b/src/bin/lttng-sessiond/kernel.c
index dee065460b1e661f8dca9f32a9070f3b876b24bc..2cbed381870a096350a4e8ac77ec39845850d0f1 100644 (file)
--- a/src/bin/lttng-sessiond/kernel.c
+++ b/src/bin/lttng-sessiond/kernel.c
@@ -16,7 +16,6 @@
  */
 
 #define _LGPL_SOURCE
-#include <errno.h>
 #include <fcntl.h>
 #include <stdlib.h>
 #include <stdio.h>
@@ -37,6 +36,8 @@
 
 /*
  * Add context on a kernel channel.
+ *
+ * Assumes the ownership of ctx.
  */
 int kernel_add_channel_context(struct ltt_kernel_channel *chan,
                struct ltt_kernel_context *ctx)
@@ -49,7 +50,7 @@ int kernel_add_channel_context(struct ltt_kernel_channel *chan,
        DBG("Adding context to channel %s", chan->channel->name);
        ret = kernctl_add_context(chan->fd, &ctx->ctx);
        if (ret < 0) {
-               switch (errno) {
+               switch (-ret) {
                case ENOSYS:
                        /* Exists but not available for this kernel */
                        ret = LTTNG_ERR_KERN_CONTEXT_UNAVAILABLE;
@@ -64,12 +65,16 @@ int kernel_add_channel_context(struct ltt_kernel_channel *chan,
                        goto error;
                }
        }
+       ret = 0;
 
 end:
        cds_list_add_tail(&ctx->list, &chan->ctx_list);
-       return 0;
-
+       ctx->in_list = true;
+       ctx = NULL;
 error:
+       if (ctx) {
+               trace_kernel_destroy_context(ctx);
+       }
        return ret;
 }
 
@@ -203,7 +208,7 @@ int kernel_create_event(struct lttng_event *ev,
 
        ret = kernctl_create_event(channel->fd, event->event);
        if (ret < 0) {
-               switch (errno) {
+               switch (-ret) {
                case EEXIST:
                        break;
                case ENOSYS:
@@ -215,7 +220,6 @@ int kernel_create_event(struct lttng_event *ev,
                default:
                        PERROR("create event ioctl");
                }
-               ret = -errno;
                goto free_event;
        }
 
@@ -236,7 +240,7 @@ int kernel_create_event(struct lttng_event *ev,
 
        ret = kernctl_enable(event->fd);
        if (ret < 0) {
-               switch (errno) {
+               switch (-ret) {
                case EEXIST:
                        ret = LTTNG_ERR_KERN_EVENT_EXIST;
                        break;
@@ -283,7 +287,6 @@ int kernel_disable_channel(struct ltt_kernel_channel *chan)
        ret = kernctl_disable(chan->fd);
        if (ret < 0) {
                PERROR("disable chan ioctl");
-               ret = errno;
                goto error;
        }
 
@@ -306,7 +309,7 @@ int kernel_enable_channel(struct ltt_kernel_channel *chan)
        assert(chan);
 
        ret = kernctl_enable(chan->fd);
-       if (ret < 0 && errno != EEXIST) {
+       if (ret < 0 && ret != -EEXIST) {
                PERROR("Enable kernel chan");
                goto error;
        }
@@ -331,7 +334,7 @@ int kernel_enable_event(struct ltt_kernel_event *event)
 
        ret = kernctl_enable(event->fd);
        if (ret < 0) {
-               switch (errno) {
+               switch (-ret) {
                case EEXIST:
                        ret = LTTNG_ERR_KERN_EVENT_EXIST;
                        break;
@@ -362,7 +365,7 @@ int kernel_disable_event(struct ltt_kernel_event *event)
 
        ret = kernctl_disable(event->fd);
        if (ret < 0) {
-               switch (errno) {
+               switch (-ret) {
                case EEXIST:
                        ret = LTTNG_ERR_KERN_EVENT_EXIST;
                        break;
@@ -393,7 +396,7 @@ int kernel_track_pid(struct ltt_kernel_session *session, int pid)
        if (!ret) {
                return LTTNG_OK;
        }
-       switch (errno) {
+       switch (-ret) {
        case EINVAL:
                return LTTNG_ERR_INVALID;
        case ENOMEM:
@@ -415,7 +418,7 @@ int kernel_untrack_pid(struct ltt_kernel_session *session, int pid)
        if (!ret) {
                return LTTNG_OK;
        }
-       switch (errno) {
+       switch (-ret) {
        case EINVAL:
                return LTTNG_ERR_INVALID;
        case ENOMEM:
@@ -579,25 +582,6 @@ void kernel_wait_quiescent(int fd)
        }
 }
 
-/*
- * Kernel calibrate
- */
-int kernel_calibrate(int fd, struct lttng_kernel_calibrate *calibrate)
-{
-       int ret;
-
-       assert(calibrate);
-
-       ret = kernctl_calibrate(fd, calibrate);
-       if (ret < 0) {
-               PERROR("calibrate ioctl");
-               return -1;
-       }
-
-       return 0;
-}
-
-
 /*
  *  Force flush buffer of metadata.
  */
@@ -666,17 +650,22 @@ error:
  * Open stream of channel, register it to the kernel tracer and add it
  * to the stream list of the channel.
  *
+ * Note: given that the streams may appear in random order wrt CPU
+ * number (e.g. cpu hotplug), the index value of the stream number in
+ * the stream name is not necessarily linked to the CPU number.
+ *
  * Return the number of created stream. Else, a negative value.
  */
 int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
 {
-       int ret, count = 0;
+       int ret;
        struct ltt_kernel_stream *lks;
 
        assert(channel);
 
        while ((ret = kernctl_create_stream(channel->fd)) >= 0) {
-               lks = trace_kernel_create_stream(channel->channel->name, count);
+               lks = trace_kernel_create_stream(channel->channel->name,
+                               channel->stream_count);
                if (lks == NULL) {
                        ret = close(ret);
                        if (ret) {
@@ -695,13 +684,10 @@ int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
                lks->tracefile_size = channel->channel->attr.tracefile_size;
                lks->tracefile_count = channel->channel->attr.tracefile_count;
 
-               /* Add stream to channe stream list */
+               /* Add stream to channel stream list */
                cds_list_add(&lks->list, &channel->stream_list.head);
                channel->stream_count++;
 
-               /* Increment counter which represent CPU number. */
-               count++;
-
                DBG("Kernel stream %s created (fd: %d, state: %d)", lks->name, lks->fd,
                                lks->state);
        }
@@ -1108,3 +1094,35 @@ int kernel_syscall_mask(int chan_fd, char **syscall_mask, uint32_t *nr_bits)
 
        return kernctl_syscall_mask(chan_fd, syscall_mask, nr_bits);
 }
+
+/*
+ * Check for the support of the RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS via abi
+ * version number.
+ *
+ * Return 1 on success, 0 when feature is not supported, negative value in case
+ * of errors.
+ */
+int kernel_supports_ring_buffer_snapshot_sample_positions(int tracer_fd)
+{
+       int ret = 0; // Not supported by default
+       struct lttng_kernel_tracer_abi_version abi;
+
+       ret = kernctl_tracer_abi_version(tracer_fd, &abi);
+       if (ret < 0) {
+               ERR("Failed to retrieve lttng-modules ABI version");
+               goto error;
+       }
+
+       /*
+        * RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS was introduced in 2.3
+        */
+       if (abi.major >= 2 && abi.minor >= 3) {
+               /* Supported */
+               ret = 1;
+       } else {
+               /* Not supported */
+               ret = 0;
+       }
+error:
+       return ret;
+}